1. Field of the Invention
The present invention relates to testing machines, and more particularly to testers which have a mechanism for quick and steady opening and closing thereof.
2. Description of the Related Art
A typical tester used for testing apparatuses such as printed circuit boards comprises a cover and a base. A control panel is formed on a front wall of the base. A retaining device is formed on a top wall of the base, for retaining a printed circuit board to be tested. The cover is parallelepiped-shaped. The cover is pivotably attached to the base, for covering the base. A testing device is provided in the cover. A knob is formed on a front wall of the cover, for opening and closing the cover. When testing a printed circuit board, an operator has to lift the cover open by the knob, fix the printed circuit board on the retaining device, and close the cover to start the test. However, such manual operation is slow, laborious and inefficient. Furthermore, if the operator opens or closes the cover too quickly, the testing device in the cover is liable to sustain damage due to shock. Accuracy of the tester may then be impaired.
Accordingly, an object of the present invention is to provide a tester which has a stable automatic opening and closing mechanism.
Another object of the present invention is to provide a tester which reduces manual labor and increases efficiency.
To achieve the above objects, a tester incorporating an opening and closing mechanism in accordance with the present invention comprises a base, a cover, a pair of first cylinders and a pair of second cylinders. The base comprises a top wall and a control panel. Three aligned and spaced lower hooks are upwardly formed on the top wall adjacent the control panel. A first sensor is mounted on a middle one of the lower hooks. The first sensor sends signals to the control panel. A pair of actuators is mounted behind the two hooks that are at apposite sides of the middle lower hook. The control panel receives and sends signals. The cover is pivotably attached to the base. Three aligned and spaced upper hooks are pivotably fixed on the cover, for engaging with the lower hooks respectively. A second sensor is mounted on the cover behind a middle one of the upper hooks. The second sensor of the cover sends signals to the control panel. Each of the first cylinders comprises a cylinder casing and a piston rod. The first cylinders are pivotably attached to the base and the cover. A third sensor is mounted on an outer surface of one first cylinder. The third sensor of the first cylinder sends signals to the control panel. The first cylinder, the second cylinders and the actuators are controlled by the control panel, for opening and closing the cover.
Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of preferred embodiments of the present invention with the attached drawings, in which: